Do Natural Enemies Impose Selection on Herbivore Diet Breadth?

Live Poster Session: Zoom Link
Thursday, July 30th 1:15-2:30pm EDT

Andrew Hennessy

Andrew is a rising senior on the wrestling team who is a Biology and Earth & Environmental Sciences major. This is his second year in the Singer Lab which focuses field ecology work in forests around Connecticut. He is planning to pursue a graduate degree and continue research in community ecology after this year.

Emily Leggat

Emily is a rising senior pursuing a major in biology. This is her second year in the Singer Lab, having previously contributed to field work investigating the effects of forest fragmentation on tri-trophic interactions. After graduation she hopes to attend graduate school to continue doing research in ecology.

Aditi Prasad

Aditi is a senior on the squash team who is a Molecular Biology and Biochemistry major. This is her first year working in the Singer Lab. Aditi is presently pursuing the pre-medical track at Wesleyan and aims to apply to medical school after she graduates.

Sydnie Rathe

Sydnie Rathe is a rising junior (’22) majoring in Biology, Earth and Environmental Sciences, and Sociology. She is a member of the RJ committee on campus and has been involved in Second Stage productions in the past. She was raised in Fort Lauderdale, FL and hopes to use the knowledge she gains in university of ecology and environmental science to aid in conservation efforts at home. She has previously worked on the Royer and Varekamp labs in the E&ES department and hopes to work in a research lab full time before potentially pursuing a Master’s in Biology.

Ben Silverstone

Ben Silverstone is an Environmental Studies and English double major in the Class of 2022, born and raised in the Greater Boston area. This is Ben’s first year in the Singer Lab. He is an avid nature-lover, an active member of the Wesleyan Outing Club, and enjoys visual art and gardening. After Wes, he hopes to pursue a graduate program that deals with conservation, habitat restoration, and ecological landscape design.

Abstract: Bernays and Graham proposed the “Enemy-Free Space” hypothesis in the paper “On the Evolution of Host Specificity in Phytophagous Arthropods” in 1988. They hypothesized that traits associated with dietary specialization would allow herbivores to better escape generalist enemies, and thus generalist enemies would select for a narrower herbivore diet breadth and dietary specialist herbivores would experience less predation and/or parasitism than dietary generalist herbivores. We performed a literature review to analyze the evidence related to the hypothesis and the herbivore traits that act as mechanisms of selection for dietary specialization. We focused particularly on four herbivore traits: the ability to sequester plant chemicals; faster growth due to better perceptual judgement; camouflage; and the ability to suppress plant volatiles. We found support that specialist herbivores sequester plant chemicals more often and utilize them for their own antipredator defenses more effectively than generalist counter parts. We also found that generalist herbivores are more likely to face issues concerning perception and decision making when faced with multiple sensory inputs, leading to longer larval growth times and more time in a very vulnerable life stage. Specialist herbivores are also more effective at employing camouflage tactics, and a negative association was found between camouflage and other defensive movements. The fourth herbivore trait, the suppression of plant emitted volatile compounds, found little support in the literature and there were more studies indicating no relationship between dietary specialization and ability to suppress induced plant volatiles. From our literature search we found overall support for the hypothesis as many specialist herbivores had more effective antipredator traits and lower mortality from generalist predators when quantitatively measured. The wide breadth of our research showed that the selection pressure can be dependent on the type of natural enemy and some traits can result in trade-offs between protection from one kind of enemy and susceptibility to another.

Singer-Lab-Summer-2020-Poster

Live Poster Session: Zoom Link
Thursday, July 30th 1:15-2:30pm EDT

Do Natural Enemies Impose Selection on Herbivore Diet Breadth?

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